Wednesday, July 22, 2009

Keeping in with our theme of spills, crashes, injuries and utter turmoil, it has always struck me as to what people do with their destroyed carbon fiber bikes after a crash. Do they trash it in the dumpster? Do they try their best and send it somewhere for a repair? Do they salvage some parts and try to use them in a different application and setting? What would you do?

This blog has shown you a number of instances in the past where bikes and bicycle components have failed. Now often there is a legitimate reason for these occurrences which I don't want to go into. But what happens afterward? What do you do with this pile of seemingly junk metal and carbon fiber?

Recently, a reader and fan of this blog - Anthony Hendrickson, with Materials & Process Engineering at Boeing Rotorcraft Systems, sent me a photo of his friend's high end Pinarello. This rider went into a turn about three wide at speed and got pushed to the outside. He wound up going into a ditch/gully running parallel to the road and the bike just broke into two pieces. Take a look :

If something like this happened to a professional bike rider, he would of course get replaced immediately with a new one. The rest of us in the world may not always have this luxury. But as bike riders, we don't want to sit without a bike for long. Eventually, the money will come and we all will get a new bike, somehow. What happens to the old one?

If it is indeed decided that it should be disposed of, is there any possibility for carbon fiber to be recycled? This is an interesting subject because it turns out it isn't so easy to do this. I have captured two different thought processes when it comes to carbon fiber as a "clean" and recyclable material for the environment. I think they will interest you because most of us call ourselves 'clean' to the environment and fans of sustainable sports and transportation. But is that really true?

A.Repairing, Reusing And Recycling Disadvantages : "Carbon fiber falls short for three strategies in the field of waste reduction - Repair, Reuse, Recycle.Repairing a carbon fiber frame often requires more expertise and time than the frame is actually worth; if it can be repaired at all. Reusing carbon fiber tubes similarly requires the same advanced skills and technology to use them for some other function. Recycling it into its component parts may be feasible in the future, but the environmental and energy ramifications of that are unknown. Carbon fiber is one of those “monstrous hybrids” the Cradle to Cradle authors deplore. When you combine organic elements with inorganic elements you often create materials that don’t break down and can cause serious problems to living systems. Carbon fiber isn’t nearly as bad as say, dioxin, but it’s still a hybrid, and the authors argue that organic nutrients and “technological nutrients” need to be kept separate." - Admin, Bicycling Is Better

Now here's an opposite viewpoint, shedding a more positive light on carbon fiber's prospects for recycling.

B. Thermal Decomposition Possibilities : "When it is time to decommission CFRPs they cannot be melted down in air like many metals. When free of vinyl (PVC or polyvinyl chloride) and other halogenated polymers, CFRPs can be thermally decomposed via thermal depolymerization in an oxygen free environment. This can be accomplished in a refinery in a one-step process. Capture and reuse of the carbon and monomers is then possible. CFRPs can also be milled or shredded at low temperature to reclaim the carbon fiber, however this process shortens the fibers dramatically. Just as with downcycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not need the strength of full-length carbon fiber reinforcement. For example, chopped reclaimed carbon fiber can be used in consumer electronics, such as laptops. It provides excellent reinforcement of the polymers used even if it lacks the strength-to-weight ratio of an aerospace component." - Wikipedia entry on CFRP's.

In light of these two statements, do you think there's a distinct possibility that carbon fiber from our trashed bicycles could be recycled and reused, or is the technology still catching up with us? Is the bicycle industry studying solutions to make this happen, or do they really want to take opportunity of this 'repair and reuse' handicap? That would mean more sales for them in terms of new bikes and equipment, so why should they bother, eh?

15 comments:

It looks like the aerospace industry is working to address CF recycling due to the large amount of CF used by them. The EU also has legislation requiring it. Good info here: http://www.compositesworld.com/articles/carbon-fiber-life-beyond-the-landfill.aspx

Dave : Steel is real, but unfortunately, its not being able to compete with the lighter stuff out there. I read an article on Design News that talks about how engineers are pretty disappointed with the quality of lightweight steels out there in the market.See : http://www.designnews.com/blog/Engineering_Materials/15527-Engineers_Are_Not_Happy_with_Steel_Quality.php?text=steel

In one of their catalogs from the late 80's or early 90's Bridgestone had short essays about the environmental impact of metal frame materials - steel, aluminum, and titanium. It would be interesting to see how composites "compete" cradle to grave.

I have some personal experience here: I put a decent crack in a Giant TCR at the top of the downtube immediately behind the headtube junction. I was going to trash it but then did a little research and found a custom canoe/kayak builder that sold carbon fiber sheet and epoxy. After calling them I discovered their lead boat/paddle builder is also a cyclist. After a long discussion he decided that the crack was indeed repairable. I spent about $120, including shipping, to buy the materials and made the repair over the space of 2 evenings in my basement. I'm no mechanical genius but the whole thing was pretty straightforward.

Some caveats:1. Upon making the repair I swore I'd never, NEVER, race this bike. It was to be strictly a training/trainer/winter/shite weather bike.2. Having said that, over 2 years of quite a bit of riding on the repair (in the winter, on the trainer, and commuting to work) I am building more and more faith in the quality of the repair.3. This was a crack. I can't imagine effecting a similar repair to a snap as in the unfortunate Pinarello.

Repairing and reusing (if possible) is far better than trashing the frame.

Let me know if you are interested in the details of what I used and I can check at home. I can't remember exactly what I used sitting here in the office.

Craig Calfee conversed with me on this topic. Here's a bit of what he wrote to me, a very interesting email indeed :

"Carbon fiber bikes can be repaired indefinitely. Unlike metals, carbon composites don't fatigue and become not worth repairing. Of course, one should evaluate the cost of repair with the value of the frame.

If cared for, they don't corrode. But they are biodegradable over time. The epoxy matrix is an amine, which can be digested by various organisms. The carbon fiber is harder to break down but it eventually does.

I had an accident working on a freshly molded carbon frame and a big carbon splinter became embedded in my leg. I went to the hospital to see about having it removed. The doc asked what it was made of and I told him. He said my body would probably digest it in a couple of years - better than surgery. Sure enough, the small lump I could feel on my shin got smaller and disappeared.

@ AH, Zhefei : I think AH was pretty lucky. Now in one of my past stories on this blog, a certain individual almost lost his Kestrel bike because he destroyed his derailleur dropout from a freak accident (see post). I personally think something like that is a bad design. If you damage it, you can't replace it. This same individual was suggested by Calfee that he buy a new frame because apparently, without the replacement Kestrel dropout, Calfee weren't able to help him.

The problem is that while there are still Kestrel bikes in the market, they really don’t have anything to do with the old Kestrel company which was bought a few years ago and folded into Fuji. So old parts and frames are no longer available.

Luckily, this person found a company called RR Velo which has a machine shop and builds custom carbon frames, and they said they were able to do the repair. So he took the bike to his local shop, had them strip all the parts off the frame and it was then sent to RR Velo.

I'm not sure how the "job" turned out but I'm interested in hearing from him (I'll try contacting him again). Supposedly, he had 40,000 miles on this frame and he would have liked to buy a new one, but he didn't have a spare 6000 dollars lying around. Not possible.

This is an excellent topic for discussion. Bicycles are so expensive and having to break one with little hope for repair but just trashing it really sounds unfair, both for the nature, and the rider. Hoping to hear other comments.

The sport of cycling, atleast on an international level, is hardly "sustainable". Just look at the Giro d'Italia or the Tour de France. Multitudes of vehicles on the road, helicopters in the air, plus look at the amount of food these competitors consume? What's the impact to the environment from all this??? Someone should really delve into this topic.

There is no recycling. The resin is cross linked polymer. It can be ground into land fill or incinerated. There is no chemical pathway to something useful; only to atoms and a devils brew of toxic fumes.